that the plant’s roots need to keep from being blown away by the fierce ocean winds. All in all quite interesting, but not worth perishing at sea.
Snorri, the naturalist assigned as my guide, confirmed that Hjalli was the only captain experienced enough to land safely at Surtsey and advised me to overlook the fact his other boat had been smashed to fiberglass bits on the jagged shoreline. All hands, after all, had survived. Besides, added Snorri, a Christian fundamentalist, the next life is bound to be better than this one.
That 1993 trip to Surtsey turned out to be an unforgettable afternoon, sliding down black aa lava tongues as long as the escalators in the London Underground, climbing into huge vagina-shaped craters and rolling around in their luscious green moss, warming our hands over fissures sputtering sulfurous steam.
After ducking a raven with a wingspan as wide as my arms, Snorri asked me if I was hungry, then had himself a good laugh. The joke went right over my head, but Rasta Cabbie would have gotten it right away. Jah, I now realize, refers to Elijah, the Old Testament prophet whose story in I Kings is what Snorri was referring to. Under the wicked King Ahab, the Hebrews had turned away from God, who decided to punish the land of Israel with three and a half years of bitter drought. God instructed Elijah to tell Ahab of the drought that would come, then flee Ahab’s wrath by hiding at the brook of Cerith, where Elijah was kept alive by ravens bringing him food.
It wasn’t until I met the Barrios brothers in Guatemala a dozen years later, however, that I understood the true import of that trip: Surtsey was my first glance at what our future might look like physically: a postvolcanic desert. What I had always back-of-the-minded as a remote if cataclysmic possibility may well be impending, as Yellowstone, one of the world’s largest supervolcanoes, gets ready to blow.
WHEN YELLOWSTONE BLOWS
How betrayed would you feel if Yellowstone, America’s first, most famous, and most exciting national park, erupted and put an end to our society? Better to feel betrayed than to feel nothing but burning sulfur choking the life out of your lungs.
The question is not if Yellowstone is going to blow, or even when. It’s not as though there’s an alarm clock inside the world’s most dangerous supervolcano, ticking toward some preset explode date. The fact is that it could erupt at any time, filling the atmosphere with sulfuric acid and ash and plunging the planet into a nuclear-winter-type catastrophe, savaging economy and agriculture so severely that civilization might never reemerge.
The supervolcano scenario is quite similar to the nuclear winter envisioned by Carl Sagan and the TTAPS group in the late 1970s. Each type of explosion creates concentric circles of doom. Ground zero of course would be scorched and purged of all living things. A Yellowstone eruption would cause much of Wyoming and Montana to quickly resemble Surtsey: black steaming rubble awaiting the droppings of birds.
The next largest circle of nuclear winter hell would be poisoned with radioactive fallout, as it might be from the Yellowstone super-volcano, which sits atop enormous uranium reserves. Winds would blow such fallout thousands of miles, fatally sickening human beings and livestock. Thyroid cancer would be the quickest illness to strike.
Those two circles of doom, infernal though they may be, would pale in lethality when compared to the effects of the ash cloud borne across the North American continent on westerly winds. Ash would clog up jet engines, render the air unbreathable, and in the long run blot out sunlight and cause temperatures to plunge and therefore crops to fail and economies to falter. The Northern Hemisphere, where some two-thirds of the world’s land mass and population is located, would see its interdependent societies collapse, as food became scarce and darkness plunged frightened psyches into depression. With the world population at nearly 6.5 billion, who can say what end of carnage and warfare might result from this calamity?
Yellowstone has had at least 100 major eruptions, three of which were unfathomably massive, each large enough to cause hemispheric calamity were it to occur today. The first eruption occurred 2 million years ago, and it was followed by another one 1.3 million years ago. According to a March 2006 Nature cover story investigating puzzling magma flows in and out of the supervolcano, Yellowstone’s most recent full-scale eruption occurred roughly 640,000 years ago and coughed out about 1,000 cubic kilometers (218 cubic miles) of ash into the atmosphere. This would be enough to bury the entire continental United States at least one meter deep in soot and cinders. It’s as though the Great Lakes were all filled twice over with ash, which was then dumped out over the continent. This is easily enough ash to block out the sunlight for the better part of a decade.
Crude math yields a periodicity of 600,000 to 700,000 years for the supervolcano’s eruptions, meaning that chronologically we are right on schedule for the next big blow.
More important than probability statistics is what’s happening underground. A guest on a BBC Horizon documentary on the Yellowstone supervolcano, Professor Robert Christiansen of the U.S. Geological Survey, recalled that he had found many rocks made of compressed ash in his visits to Yellowstone, but for years he could never find any evidence of the volcano from which they must certainly have erupted. He consoled himself with the thought that it must be very tiny. That thought exploded in 1993 when NASA, testing some infrared photographic equipment designed for scanning the Moon, took heat signature photos of Yellowstone and revealed the largest single caldera ever discovered. Calderas are large underground depressions containing magma, a mixture of solid and liquefied rock and highly combustible volcanic gases. The Yellowstone caldera is unbelievably huge, the size of the city of Tokyo, some 40 to 50 kilometers long and 20 kilometers wide, the molten, beating heart of Yellowstone Park.
Subsequent geological surveys revealed that the caldera (which means “cauldron”) has risen about 3/4 meter since 1922, filling with magma and getting ready to explode. Compared to other geological timescales, such as the millimeter-per-century continental drift and the virtually imperceptible weathering of mountains, such a change is downright tumultuous.
As Robert B. Smith, a geologist and geophysicist at the University of Utah, reports, this supervolcano’s topographical distortion is so pronounced that Yellowstone Lake, which sits atop the caldera, is now actually tilting because of the bulge. Water is draining out at the south end, inundating trees that just a few years earlier grew normally out of the soil along the shore.
“It would be extremely devastating, on a scale we’ve probably never even thought about,” says Smith of the coming Yellowstone eruption. Estimates of its explosive force range up to the equivalent of 1,000 Hiroshima-style atomic bombs—per second. This would be roughly the equivalent of all the violent energy ever expended in all the wars ever fought, per minute.
“I’m not sure what we would do,” says Steve Sparks, a professor of geology at the University of Bristol, of a Yellowstone eruption, “except stay underground.”
Supervolcanoes are quite different from the cone-shaped volcanoes with which we are familiar. They are depressions in the ground, from several hundred to more than a thousand miles deep, usually with complex networks of rivulets, tubes, and tributaries through which magma can flow. There is some disagreement on how supervolcanoes’ deep structures operate; most appear to channel magma and explosivity from deep in the mantle, the thick, liquidy layer between the crust and the core that accounts for most of the Earth’s volume.
Supervolcanoes are far more powerful than conventional volcanoes. By definition, they measure 8 on the volcanic explosivity index (VEI), which runs from 1 to 8. Like the Richter scale for earthquakes, VEI is logarithmic, meaning that each number indicates a blast ten times greater than the preceding number. Mount St. Helens, considered a large blast, was a VEI 5.
Other supervolcanoes around the world include Kikai Caldera in Ryukyu Islands, Japan;
